Apparatuses and methods for selecting a transport control mechanism

ABSTRACT

The present invention proposes an apparatus and a method for selecting a transport control mechanism to be used between a first device ( 110 ) and a second device ( 120 ). Firstly, a first unit ( 231 ) obtains first information indicating the transport control mechanism supported by the first device ( 210 ) and second information indicating the transport control mechanism supported by second device ( 220 ); then, a second unit ( 232 ) selects the transport control mechanism to be used between the first device ( 210 ) and the second device ( 220 ) on the basis of the first and second information and a preset rule. With the apparatuses and methods provided in the present invention, the problem of how to select the transport control mechanism to be used between the media server and the media client is well solved. Furthermore, by applying the defined messages and the interaction process in IGRS protocols, there is no need for additional messages nor for an additional interaction process.

TECHNICAL FIELD

The present invention relates to apparatuses and methods for selecting atransport control mechanism to be used between a first device and asecond device, in particular between a media server and a media client.

BACKGROUND OF THE INVENTION

FIG. 1 depicts the overall architecture of an IGRS AV (IntelligentGrouping and Resource Sharing, Audio/Video profile) system, in which 3logical units are defined, namely the media server 110, the media client120 and the controller 130. The media server 110 is where content islocated and managed, the media client 120 is where content is played andcan be either a media player or a media recorder, while the controller130 is the coordination unit between the media server 110 and the mediaclient 120, and said controller can determine the interaction process ofan audio/video application between the media server 110 and the mediaclient 120. In the IGRS AV system, general device/service discovery,service invocation are governed by an IGRS core protocol, while AVspecific control (such as multimedia content playback session setup andcontrol) is governed by an IGRS AV protocol, and actual stream transportbetween the media server 110 and the media client 120 is fully out ofband. For the stream transport control, there are two mechanisms: SOAP(Simple Object Access Protocol) based transport control and BCM(Back-Channel Message) based transport control. If the two streamtransport control mechanisms are both supported in the media server 110and the media client 120, a problem that needs to be solved relates tohow either one of them is chosen to be operative.

SUMMARY OF THE INVENTION

The present invention proposes a technical solution for selecting atransport control mechanism to be used between a first device and asecond device.

According to another embodiment of the present invention, there isprovided an apparatus for selecting a transport control mechanism to beused between a first device and a second device, comprising: a firstunit for obtaining first information indicating the transport controlmechanism supported by the first device and second informationindicating the transport control mechanism supported by the seconddevice; and a second unit for selecting the transport control mechanismto be used between the first device and the second device on the basisof the first and second information and a preset rule.

According to an embodiment of the present invention, there is provided amethod of selecting a transport control mechanism to be used between afirst device and a second device, comprising: obtaining firstinformation indicating the transport control mechanism supported by thefirst device and second information indicating the transport controlmechanism supported by second device; and selecting the transportcontrol mechanism to be used between the first device and the seconddevice on basis of the first and second information and a preset rule.

With the apparatuses and methods provided in the present invention, theproblem of how to select the transport control mechanism to be usedbetween the media server and the media client is well solved.Furthermore, by applying the defined messages and interaction process inthe IGRS protocols, there is no need for additional messages nor for anadditional interaction process to make a selection.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, characteristics and merits of the presentinvention will become more apparent from the following detaileddescription considered in connection with the accompanying drawings, inwhich:

FIG. 1 illustrates the overall architecture of an IGRS AV system, inwhich 3 logical units are defined, namely the media server 110, themedia client 120 and the controller 130;

FIG. 2 illustrates a scenario according to an embodiment of the presentinvention, including a first device 210, a second device 220 and anapparatus 230 for selecting a transport control mechanism to be usedbetween the first device 210 and the second device 220;

FIG. 3 illustrates a schematic view of a block diagram of the first unit231 according to an embodiment of the present invention;

FIG. 4 illustrates a schematic view of a block diagram of the first unit231 according to another embodiment of the present invention;

FIG. 5 illustrates a schematic view of a block diagram of the apparatus230 according to another embodiment of the present invention;

FIG. 6 illustrates an interaction process of selecting a transportcontrol mechanism for an IGRS AV system in a scenario of SOAP based andBCM based transport control mechanisms co-existing according to anembodiment of the present invention;

FIG. 7 illustrates a flowchart of selecting a transport controlmechanism to be used between a first device 110 and a second device 120according to another embodiment of the present invention;

FIG. 8 illustrates a flowchart of the substeps of step S701 in FIG. 7according to an embodiment of the present invention;

FIG. 9 illustrates a flowchart of the substeps of step S701 in FIG. 7according to an embodiment of the present invention.

In the drawings, same or analogous reference numerals refer to same oranalogous step features/devices (modules) throughout the Figures.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments of the present invention are described indetail with reference to the accompanying drawings.

FIG. 2 illustrates a scenario according to an embodiment of the presentinvention, including a first device 210, a second device 220 and anapparatus 230 for selecting a transport control mechanism to be usedbetween the first device 210 and the second device 220. The apparatus230 includes a first unit 231 and a second unit 232.

Firstly, the first unit 231 obtains first information indicating thetransport control mechanism supported by the first device 210 and secondinformation indicating the transport control mechanism supported by thesecond device 220.

Secondly, the second unit 232 selects the transport control mechanism tobe used between the first device and the second device on the basis ofthe first and second information and a preset rule. In an embodiment,the preset rule is a user's preferential configuration setting. Inanother embodiment, the preset rule is a default setting.

In an embodiment, the first unit 231 further comprises a first module2311 and a second module 2312 for obtaining the first informationindicating the transport control mechanism supported by the first device210, as shown in FIG. 3.

Firstly, the first module 2311 sends a request message requesting atleast part of the first information to the first device 210.

When the first device 210 receives the request message, it will respondwith a response message comprising at least part of the firstinformation.

Then, the second module 2312 receives a response message comprising atleast part of the first information from the first device 210.

If the first device 210 supports several kinds of transport controlmechanisms, the first information can be obtained through a singlesignaling interaction or a plurality of signaling interactions; in eachof the plurality of interactions, part of the first information isobtained. The specific form of the request message and the responsemessage for the first information can be varied using differenttransport control mechanisms supported by the first device 210, whichwill be illustrated by means of the following examples.

In an embodiment, the first unit 231 further comprises a third module2313 and a fourth module 2314 for obtaining the second informationindicating the transport control mechanism supported by the seconddevice 220, as shown in FIG. 4.

Firstly, the third module 2313 sends a request message requesting atleast part of the second information to the second device 220.

When the second device 220 receives the request message, it will respondwith a response message comprising the at least part of the secondinformation.

Then, the second module 2314 receives a response message comprising thesecond information from the second device 220.

If the second device 220 supports several kinds of transport controlmechanisms, the second information can be obtained through a singlesignaling interaction or a plurality of signaling interaction; in eachof the plurality of interactions, part of the second information isobtained. The specific form of the request message and the responsemessage for the second information can be varied using differenttransport control mechanisms supported by the second device 210, whichwill be illustrated by means of the following examples.

It is to be understood that the modules in FIG. 3 and FIG. 4 are justfor illustration; the first unit 231 can obtain the first and secondinformation in other ways, such as by just receiving an initiativereport from the first and second device, or obtaining the first andsecond information from another device etc.

Advantageously, in an embodiment, the apparatus 230 further comprises athird unit 233 and a fourth unit 234, respectively, for notifying thefirst device 210 and the second device 220 of the selected transportcontrol mechanism selected by the second unit 232, as shown in FIG. 5.

In an embodiment, for an IGRS AV system shown in FIG. 1, the firstdevice 210 can be the media server 110, the second device 220 can be themedia client 120. The apparatus 230 can be located in the controller130, or the controller 130 can achieve the function implemented by theapparatus 230. It is to be understood that the first device 210 can bethe media client 120, and the second device 220 can be the media server110.

If media server 110 supports a SOAP based transport control mechanism,then Content Index Service (CIS), Connection Management Service (CMS),and Media Server Transport Management Service (MSTMS) are realized inmedia server 110 to perform the transport control of the stream betweenthe media server 110 and the media client 120.

CIS allows the controller 130 to discover the media content and list iton the media server 110, so that the controller 130 can retrieve thecontent information, including the name, creation date, size, formatetc. of media content. This information can be used by the controller130 to determine whether these contents can be played on the mediaclient 120.

CMS is used to create and manage the connection between the media server110 and the media client 120. The media server 110 can support andmanage several active connections at any time by means of CMS.

The optional MSTMS enables the controller 130 to adjust and control themedia stream transport on the media server 110, such as play, pause,stop, seek etc. If this service exists, it means that the “Push” Mode issupported, which means the media server 110 will initiate the mediastream transport. Otherwise, it is not supported.

If the media client 120 supports a SOAP based transport controlmechanism, then Rendering Management Service (RMS), ConnectionManagement Service (CMS), and Media

Client Transport Management Service (MCTMS) are realized in the mediaclient 120 to perform the transport control of the stream between themedia server 110 and the media client 120.

RMS allows the controller 130 to control media rendering, such asvolume, contrast, brightness etc. Multiple active instances of renderingcontrol can be supported, such as the “picture-in-picture” function inTV. A new RMS instance is created by PrepareForConnection of CMS on themedia client 120. This service is only provided by the media client 120.

CMS is used to create and manage the connection between the media server110 and the media client 120. The media client 120 can support andmanage multiple active connections at any time by means of CMS. CMSimplementation is the same on both the media client 120 and the mediaserver 110.

The optional MCTMS service enables the controller 130 to adjust andcontrol the transport of a media stream on the media client 120, such asplay, pause, stop, seek etc. If this service exists, it means that the“Pull” Mode is supported, which means the media client 120 will initiatethe media stream transport. Otherwise, it is not supported.

A Back-Channel is a pipe between the media server 110 and the mediaclient 120 set up for out-of-band transport control. A Back-Channel isset up between a BCM (Back-Channel Message) Server and a Client, andcommands, notifications and error messages can be transported in thischannel. If media server 110 supports the BCM based transport controlmechanism, then the Content Index Service (CIS) and BCM Server arerealized by the media server 110 to perform the transport control of astream between the media server 110 and the media client 120. If mediaclient 120 supports the BCM based transport control, the BCM Client isrealized by the media client 120 to perform the transport control of astream between the media server 110 and the media client 120.

In existing IGRS AV systems, only one transport control mechanism isimplemented, being either a SOAP based transport control mechanism or aBCM based transport control mechanism; there is no need to choose. Butif both SOAP based and BCM based transport control mechanisms areimplemented by the IGRS AV system, the issue that needs to be resolvedrelates to how either one of them is chosen to be operative.

FIG. 6 shows an interaction process of selecting a transport controlmechanism for an IGRS AV system in a scenario of SOAP based and BCMbased transport control mechanisms co-existing according to anembodiment of the present invention.

Firstly, in step S601, the controller 130 sends a request message to themedia server 110 requesting it to browse the content to be transportedand played by the media client 120, and subsequently gets a responsemessage indicating the content from the media server 110, which can beimplemented by CIS:Browse defined in the IGRS AV profile standard.

Secondly, in step S602, the controller 130 sends a request message tothe media server 110 requesting it to search services provided by themedia server 110, and subsequently receives a response messageindicating the services provided by the media server 110 from the mediaserver 110, which can be achieved by the SearchServiceRequestOnDevicemessage and the SearchServiceResponseOnDevice message defined in theIGRS protocol. The SearchServiceResponseOnDevice message comprises aServiceInfoList comprising MSTMS if a SOAP based transport controlmechanism is supported by the media server 110. Alternatively, thecontroller 130 sends a SearchServiceRequest message to a multicastaddress 239.255.255.250:1900 to search services provided by a group ofdevices including the media server 110. The media server 110 responds tothe SearchServiceRequest message with a SearchServiceResponse messagecomprising a ServiceInfoList. The ServiceInfoList will comprise MSTMS ifthe SOAP based transport control mechanism is supported by the mediaserver 110. Specifically, the step of sending and receiving can beperformed by, respectively, the first module 2311 and the second module2312 of the first unit 231 of the apparatus 230 in the controller 130.

Thirdly, in step S603, the controller 130 sends a request message to themedia client 120 requesting it to search services provided by the mediaclient 120, and subsequently receives a response message from the mediaclient 120, which can be achieved by the SearchServiceRequestOnDevicemessage and the SearchServiceResponseOnDevice message defined in IGRSprotocols. The SearchServiceResponseOnDevice message comprises a

ServiceInfoList comprising MCTMS if a SOAP based transport controlmechanism is supported by the media client 120. Alternatively, thecontroller 130 sends a SearchServiceRequest message to a multicastaddress 239.255.255.250:1900 requesting it to search services providedby a group of devices including the media client 120. The media client120 responds to the SearchServiceRequest message with aSearchServiceResponse message comprising a ServiceInfoList. TheServiceInfoList will comprise MCTMS if the SOAP based transport controlmechanism is supported by the media client 120. Specifically, the stepof sending and receiving can be performed by, respectively, the thirdmodule 2313 and the fourth module 2314 of the first unit 231 of theapparatus 230 in the controller 130.

Then, in step S604, the controller 130 sends a request message to themedia server 110 to get the transport protocol information, transportcontrol protocol and media format supported by the media server 110.Then the controller 130 receives a response message comprising thetransport protocol information, transport control protocol and mediaformat supported by the media server 110 from the media server 110,which can be achieved by a GetProtocolInfoRequest message andGetProtocolInfoResponse message defined in the IGRS AV profile standard.The GetProtocolInfoResponse message will indicate the transport controlprotocol is BCM if the BCM based transport control mechanism issupported by the media server 110. Specifically, the step of sending andreceiving can be performed by, respectively, the first module 2311 andthe second module 2312 of the first unit 231 of the apparatus 230 in thecontroller 130.

Similarly, in step S605, the controller 130 sends a request message tothe media client 120 requesting it to get the transport protocolinformation, transport control protocol and media format supported bythe media client 120. Then, the controller 130 receives a responsemessage comprising the transport protocol information, transport controlprotocol and media format supported by the media client 120 from mediaclient 120, which can be achieved by a GetProtocolInfoRequest messageand GetProtocolInfoResponse message defined in the IGRS AV profilestandard. The GetProtocolInfoResponse message will indicate thetransport control protocol is BCM if the BCM based transport controlmechanism is supported by the media client 120. Specifically, the stepof sending and receiving can be performed by, respectively, the thirdmodule 2313 and the fourth module 2314 of the first unit 231 of theapparatus 230 in the controller 130.

It is to be understood that FIG. 5 is only an illustration. Step S602and step S603 can be performed before step S601. Step S602 and step S603do not have to be performed in a fixed sequence, i.e. step S603 can beperformed before step S602 or together with step S602. Step S604 andstep S605 do not have to be performed in a fixed sequence, i.e. stepS605 can be performed before step S604 or together with step S604.

After getting the transport protocol information and media formatsupported by, respectively, the media server 110 and the media client120, in step S606, the controller 130 selects a transport protocol andmedia format to be used between the media server 110 and the mediaclient 120. For the transport protocol, for instance, if the mediaserver 110 only supports the HTTP protocol, then the media client 120should also support the HTTP protocol to start the transport. Similarly,for the media format, if the media server 110 supports MPEG2 TS, H.264for a certain content, and the media client 110 supports MPEG2 TS, WMV,then the controller 130 will select MPEG2 TS as the media format forthat content.

For the transport control protocol, i.e. transport control mechanism, instep S607, the second unit 232 of the apparatus 230 in the controller130 selects a transport control mechanism to be used between the mediaserver 110 and the media client 120 on the basis of the first and secondinformation and a preset rule. The first information indicating thetransport control mechanism supported by the media server 110 comprisesthe information indicating whether the media server 110 supports a SOAPbased transport control mechanism or not and the information indicatingwhether the media server 110 supports a BCM based transport controlmechanism or not. The former is obtained by theSearchServiceResponseOnDevice message or the SearchServiceResponsemessage and the latter is obtained by the GetProtocolInfoResponsemessage. Similarly, the second information indicating the transportcontrol mechanism supported by the media client 120 comprises theinformation indicating whether the media client 120 supports a SOAPbased transport control mechanism or not and the information indicatingwhether the media client 120 supports a BCM based transport controlmechanism or not. The former is obtained by theSearchServiceResponseOnDevice message or the SearchServiceResponsemessage and the latter is obtained by the GetProtocolInfoResponsemessage.

The preset rule can be different, based on different transport controlmechanisms supported by the media server 110 and the media client 120.If both the media server 110 and the media client 120 support the SOAPbased and BCM based transport control mechanisms, the preset rule can bea default setting or a user's preferential configuration setting. Forexample, the default setting can be a BCM based transport controlmechanism. The user's preferential configuration setting can be also aBCM based transport control mechanism. If both a default setting and auser's preferential configuration setting exist, the preset rule can bethe user's preferential configuration setting.

If the media client 120 only supports one kind of transport controlmechanism, while the media server 110 supports two kinds of transportcontrol mechanisms, then the preset rule selects the kind of transportcontrol mechanism supported by the media client 120. The selection issimilar when the media server 110 only supports one kind of transportcontrol mechanism while the media client 120 supports two kinds oftransport control mechanisms.

It is to be understood that step S606 and step S607 do not have to beperformed in a fixed sequence, i.e. step S607 can be performed beforestep S606 or together with step S606.

When the selection is done, the controller 130 can further notify themedia server 110 and the media client 120 of the selected transportcontrol mechanism. This can be achieved by an additional signalinginteraction process, or by the defined signaling interaction process inthe IGRS AV profile standard. For example, if a SOAP based transportcontrol mechanism is selected, then the controller 130 sends aCMS:PrepareForConnnectionRequest message to, respectively, the mediaserver 110 and the media client 120. When the media server 110 and themedia client 120 receive the CMS:PrepareForConnnectionRequest message,they will realize that the SOAP based transport control protocol isselected to control the stream transport between them. Then MCTMS andMSTMS will be invoked by, respectively, the media client 120 and themedia server 110 to realize the transport control between the mediaclient 120 and the media server 110.

In the case of the controller 130 and the media client 120 beingimplemented together in a physical device, the interaction process inFIG. 6 between the controller 130 and the media client 120 can beomitted. In such a situation, if a BCM based transport control mechanismis selected, then the controller 130 sends a BCM:Play message to themedia server 110. When the media server 110 receives the BCM:Playmessage, it will realize that the BCM based transport control protocolis selected to control the stream transport. Then BCM client and BCMserver are invoked to realize the transport control between,respectively, the media client 120 and the media server 110.

Similarly, in the case of the controller 130 and the media server 110being implemented together in a physical device, the interaction processin FIG. 6 between the controller 130 and the media server 110 can alsobe omitted.

From FIG. 6, it can be seen that the request message requesting at leastpart of the first or second information and the response messagecomprising the at least part of the first or second information can beimplemented by the defined messages in the IGRS AV protocols. Noadditional message type and additional interaction process are neededfor the controller 130 to obtain the first and second information and tonotify the media client 120 and the media server 110 of the selectedtransport control protocol.

FIG. 7 shows a flowchart of selecting a transport control mechanism tobe used between a first device 110 and a second device 120.

Firstly, in step S701, first information is obtained indicating thetransport control mechanism supported by the first device 210 and secondinformation is obtained indicating the transport control mechanismsupported by the second device 220. In an embodiment, step S701 can beperformed by the first unit 231 of the apparatus 230.

Secondly, in step S702, the transport control mechanism is selected thatis to be used between the first device and the second device on thebasis of the first and second information and a preset rule. In anembodiment, the step S702 can be performed by the second unit 232 of theapparatus 230.

In an embodiment, the preset rule is a user's preferential configurationsetting. In another embodiment, the preset rule is a default setting.

In an embodiment, the step S701 can further comprise two substeps forobtaining the first information indicating the transport controlmechanism supported by the first device 210, as shown in FIG. 8.

Firstly, in step S801, a request message requesting at least part of thefirst information is sent to the first device 210. In one embodiment,the step S801 can be performed by first module 2311 of the first unit231 of the apparatus 230.

When the first device 210 receives the request message, it will respondwith a response message comprising the at least part of the firstinformation.

Then, in step S802, a response message is received comprising at leastpart of the first information from the first device 210. In anembodiment, the step S802 can be performed by second module 2312 of thefirst unit 231 of the apparatus 230.

If the first device 210 supports several kinds of transport controlmechanisms, the first information can be obtained through a singlesignaling interaction or a plurality of signaling interactions, whereinin each of the plurality of interactions, part of the first informationis obtained, i.e. the substeps S801 and S802 can be performed severaltimes to obtain all of the first information.

In an embodiment, the step S701 may further comprise another twosubsteps for obtaining the second information indicating the transportcontrol mechanism supported by the second device 220, as shown in FIG.9.

Firstly, in step S901, a request message requesting at least part of thesecond information is sent to the first device 220. In an embodiment,the step S901 can be performed by the third module 2313 of the firstunit 231 of the apparatus 230.

When the second device 220 receives the request message, it will respondwith a response message comprising the at least part of the secondinformation.

Then, in step S902, a response message comprising the second informationis received from the second device 220. In an embodiment, the step S902can be performed by fourth module 2314 of the first unit 231 of theapparatus 230.

If the second device 220 supports several kinds of transport controlmechanisms, the second information can be obtained through a singlesignaling interaction or a plurality of signaling interactions, whereinin each of the plurality of interactions, part of the second informationis obtained, i.e. the substeps S901 and S902 can be performed severaltimes to obtain all of the second information.

It is to be understood that the substeps in FIG. 8 and FIG. 9 are justfor illustration; the first and second information can be obtained inother ways such as by just receiving an initiative report from the firstand second device, or obtaining the first and second information fromanother device, etc.

Advantageously, in an embodiment, the flowchart in FIG. 7 can furthercomprise a step of notifying, respectively, the first device 210 and thesecond device 220 of the selected transport control mechanism selectedby the second unit 232, which can be performed by the third unit 233 andthe fourth unit 234 of the apparatus 230 in one embodiment.

The function of the apparatus 230 and the flowcharts in FIG. 7 to FIG. 9are fully described in the above paragraphs. It should be understoodthat the application of the apparatus 230 and the flowcharts in FIG. 7to FIG. 9 is not limited to an IGRS AV system. For other scenarios of atransport control mechanism to be selected, the apparatus 230 and theflowcharts in FIG. 7 to FIG. 9 are also applicable.

It is further to be understood that the apparatus 230 is described interms of its function only. The apparatus 230 or each unit therein, suchas the first unit 231 and/or the second unit 232 etc., can beimplemented by hardware or a combination of software and hardware. Forexample, they could be implemented by a processor linked to a memorystoring the instruction code for implementing the function of the firstunit 231 and/or the second unit 232. Some of the modules and/or theunits of the apparatus 230 can share the same physical module upon theirimplementation. For example, the third module 2313 and the fifth module2315 can share the same physical module.

It should be noted that the above-described embodiment is for thepurpose of illustration only and not to be construed as a limitation ofthe invention. All such modifications which do not depart from thespirit of the invention are intended to be included within the scope ofthe appended claims. In the claims, any reference signs placed betweenparentheses shall not be construed as limiting the claim. The word“comprising” does not exclude the presence of elements or steps notlisted in a claim or in the description. The word “a” or “an” precedingan element does not exclude the presence of a plurality of suchelements. In the apparatus claims enumerating several units, several ofthese units can be embodied by one and the same item of hardware orsoftware. The use of the words first, second and third, et cetera, doesnot indicate any ordering. These words are to be interpreted as names.

What is claimed is:
 1. An apparatus for selecting a stream transportcontrol mechanism to be used between a first device and a second device,comprising: a first unit for obtaining first information indicating astream transport control mechanism supported by the first device andsecond information indicating a stream transport control mechanismsupported by the second device, wherein the stream transport controlmechanism comprises both a Simple Object Access Protocol (SOAP) basedtransport control mechanism and a Back-Channel Message (BCM) basedtransport control mechanism; and a second unit for selecting the streamtransport control mechanism to be used between the first device and thesecond device on the basis of the obtained first information, theobtained second information, and a preset rule, wherein the preset ruleis different as determined based on (i) stream transport controlmechanisms supported by the first device as indicated via the obtainedfirst information and (ii) stream transport control mechanisms supportedby the second device as indicated via the obtained second information,said second unit selecting only a single mechanism, either SOAP or BCM,to be operative in response to both SOAP and BCM being supported by boththe first device and the second device.
 2. The apparatus according toclaim 1, wherein the preset rule further comprises a user's preferentialconfiguration setting.
 3. The apparatus according to claim 1, whereinthe preset rule further comprises a default setting.
 4. The apparatusaccording to claim 1, wherein the first unit comprises: a first moduleconfigured to send a request message requesting at least part of thefirst information to the first device; and a second module configured toreceive a response message that comprises at least part of the firstinformation from the first device.
 5. The apparatus according to claim1, wherein the first unit further comprises: a third module configuredto send a request message requesting at least part of the secondinformation to the second device; and a fourth module configured toreceive a response message that comprises at least part of the secondinformation from the second device.
 6. The apparatus according to claim1, further comprising: a third unit configured to notify the firstdevice of the selected stream transport control mechanism; and a fourthunit configured to notify the second device of the selected streamtransport control mechanism.
 7. A method of selecting a stream transportcontrol mechanism to be used between a first device and a second device,comprising: obtaining first information indicating a stream transportcontrol mechanism supported by the first device and second informationindicating a stream transport control mechanism supported by the seconddevice, wherein the stream transport control mechanism comprises both aSimple Object Access Protocol (SOAP) based transport control mechanismand a Back-Channel Message (BCM) based transport control mechanism; andselecting the stream transport control mechanism to be used between thefirst device and the second device on the basis of the first obtainedinformation, the obtained second information, and a preset rule, whereinthe preset rule is different as determined based on (i) stream transportcontrol mechanisms supported by the first device as indicated via theobtained first information and (ii) stream transport control mechanismssupported by the second device as indicated via the obtained secondinformation, selecting only a single mechanism, either SOAP or BCM, tobe operative in response to both SOAP and BCM being supported by boththe first device and the second device.
 8. The method according to claim7, wherein the preset rule further comprises a user's preferentialconfiguration setting.
 9. The method according to claim 7, wherein thepreset rule further comprises a default setting.
 10. The methodaccording to claim 7, wherein the step of obtaining the firstinformation comprises: sending a request message requesting at leastpart of the first information to the first device; and receiving aresponse message that comprises at east part of the first informationfrom the first device.
 11. The method according to claim 7, wherein thestep of obtaining the second information comprises: sending a requestmessage requesting at least part of the second information to the seconddevice; and receiving a response message that comprises at least part ofthe second information from the second device.
 12. The method accordingto claim 7, further comprising the following step: notifying the firstdevice and the second device of the selected stream transport controlmechanism.